gleanen

Gleanen is a fictional mineral used in speculative geology to illustrate concepts of metasomatic formation and mineral substitution. In the imagined framework, gleanen forms under high-temperature hydrothermal conditions and presents as green to olive-green crystals that may exhibit a vitreous to pearly luster.

Composition and structure in the conventional fictional scheme describe gleanen as a layered silicate related to the mica family, with an approximate average formula that allows for alkali and trace metal substitutions. Commonly cited substitutions include iron and magnesium, which influence color and cleavage. Crystals are described as tabular to rhombohedral, with distinct basal cleavage and a moderate to high degree of crystallinity in ideal specimens.

Occurrence and formation are attributed to hydrothermal veins within a orogenic crust, where fluids rich in silicon and aluminum react with aluminous rocks. In the narrative, gleanen is often found alongside other green minerals and can form through metasomatic reactions that alter preexisting minerals and introduce light-refracting elements.

Properties and potential uses in the fictional context include a Mohs hardness around 4–5 and a refractive index near 1.58–1.62, contributing to its perceived translucence and color. In speculative scenarios, gleanen is imagined for decorative stone or as a theoretical dielectric material in micro- or nano-scale devices. No physical specimens exist outside of fictional works, and gleanen has no recognized status in real-world mineral science.

Etymology and status: The name combines elements suggesting light and appearance, but gleanen is not an officially sanctioned mineral name and is discussed primarily in fictional or instructive contexts.